1. Field of the Invention
The present invention relates to a mis-insertion protection mechanism in a magnetic or optical disk cartridge for preventing the cartridge from being inserted into a disk drive in a wrong direction.
2. Description of the Related Art
A magnetic or optical disk cartridge is generally in a rectangular shape and has a window opened for receiving an optical pickup and a shutter for opening/closing the window. There are two types of such cartridges: a single-sided cartridge (for use with a single-sided disk) and a double-sided cartridge (for use with a double-sided disk). A single-sided cartridge can be inserted into a disk drive only in one direction. A double-sided cartridge can be inserted into a disk drive in either one of two directions (i.e., it can be inserted with either one of the front side and the reverse side facing up). When a cartridge is inserted in a direction other than the right direction(s), a mis-insertion protection mechanism in the cartridge hits a stopper provided in the disk drive so that the cartridge cannot be inserted any further.
A conventional single-sided cartridge has a mis-insertion protection mechanism provided by differently shaping one of the four corners from the other corners. For example, as shown in FIG. 12, a 3.5" floppy disk cartridge 101 includes a corner 102 on the front edge thereof, which is chamfered. The other three corners 103, 104 and 105 of the cartridge 101 are rounded for easy insertion and easy handling of the cartridge 101, as well as for an aesthetic design.
FIG. 13 illustrates an exemplary cartridge holder 106 for use in a disk drive receiving the cartridge 101. The cartridge holder 106 is provided with a mis-insertion protection pin 107 made of a torsion spring. One end of the mis-insertion protection pin 107 is bent at about 90.degree., thereby forming a stopper 108, and the other end 107A is secured on an outer surface of the cartridge holder 106.
The stopper 108 extends through a guide hole 109 of the cartridge holder 106 to be within the insertion path of the cartridge 101 (i.e., a path along which the cartridge 101 is inserted). The stopper 108 abuts a tab portion 110 of the cartridge holder 106 and is urged away from a side 111 thereof by virtue of the bias of the torsion spring.
Referring to FIGS. 14, 15 and 16, a mis-insertion protection function provided when the cartridge 101 is inserted into the cartridge holder 106 will be described. First, a case where the cartridge 101 is inserted correctly (in the right direction) will be described. As the cartridge 101 is inserted into the cartridge holder 106 in the right direction as illustrated in FIG. 14, the chamfered corner 102 hits the stopper 108.
Since the corner 102 is chamfered, the insertion of the cartridge 101 forces the stopper 108 out of the insertion path of the cartridge 101 by overcoming the bias of the torsion spring (in the direction indicated by arrow A in FIG. 14), thereby resulting in a state as illustrated in FIG. 15. Thus, the cartridge 101 is allowed to be inserted further into the cartridge holder 106.
Next, a case where the cartridge 101 is inserted in a wrong direction will be described referring to FIG. 16. As the cartridge 101 is inserted into the cartridge holder 106 in the wrong direction as illustrated in FIG. 16, the corner 103 hits the stopper 108. Since the corner 103 is not chamfered, the insertion of the cartridge 101 does not force the stopper 108 in the direction indicated by arrow A.
Therefore, the cartridge 101 cannot be inserted further into the cartridge holder 106, thus providing the mis-insertion protection function. The mis-insertion protection function is similarly provided when the cartridge 101 is inserted from the corner 104 (or 105) (FIG. 12).
Japanese Laid-Open Publication No. 57-113466 describes an exemplary mis-insertion protection mechanism for a double-sided cartridge as illustrated in FIG. 17. Both of the insertion-side corners 172A and 172B are chamfered, so that the cartridge exhibits the same profile whether it is faced up or faced down. Thus, the cartridge can be inserted into the cartridge holder whether it is faced up or faced down.
Regarding the optical disk, there are one-sided optical disks (having a recording surface only on one side) and double-sided optical disks (having a recording surface on both sides). Recently, there is a need in the art to accommodate a single-sided disk in a single-sided cartridge and a double-sided disk in a double-sided cartridge, respectively, so that they can be used in the same disk drive. Along with the increase in the recording density of an optical disk, there is also a demand in the art for a cartridge accommodating a small-diameter optical disk.
Since a pickup for optical disks is larger than a magnetic recording pickup, an optical disk cartridge has a larger window and also requires a larger area for the motion of the shutter ("shutter motion area"). Therefore, in a cartridge accommodating a small-diameter optical disk, the shutter motion area comes close to the side edges, and thus the corners, of the cartridge.
In such an optical disk cartridge desired in the art, it is difficult to provide a mis-insertion protection mechanism by differentiating the shape of one or two corner(s) from that of the other corners as in the prior art. This is because it is difficult to provide a large enough chamfer at the corner(s) to differentiate the corner(s) from the other rounded corners such that a mis-insertion protection function can be provided.